Anionic surfactant, particularly, alkyl sulfate and alkyl polyoxyalkylene sulfate, is excellent in detergency and foaming power, and thus are widely used as cleansing ingredients for domestic or industrial use. An olefin sulfonate, particularly, an internal olefin sulfonate obtained with an internal olefin having a double bond inside an olefin chain, not at its end, as a raw material, has been reported as one of the anionic surfactants.
Such an internal olefin sulfonate is generally obtained by sulfonating an internal olefin through reactions with a gaseous sulfur trioxide-containing gas, followed by neutralization and then hydrolysis of the resulting sulfonic acid. For example, Patent Document 1 discloses an improved production method thereof. The internal olefin sulfonate thus obtained is known to have good biodegradability or the like, but is still insufficient in a basic performance as cleansing agent including foamability and foam quality, compared with general-purpose surfactant such as alkyl polyoxyalkylene sulfuric acid ester salt. Thus, further improvement in such basic performance has been desired. As more people have concerned the water-saving or consumers' preferences have been diversified in recent years, the additional value of having excellent foam spreadability and foam dissipation property in addition to good foamability has also been required for use as major activator in laundry detergents, dishwashing detergents, shampoos or the like. Specifically, it has been desired to develop a surfactant composition having excellent foam spreadability that enables a cleansing target to be covered with foam in a short time by rapidly spreading foam, and excellent foam dissipation property that permits shortening of rinsing time. Such an additional value is useful for, for example, hair shampoos. As more people have a habit to wash their hair within a limited time before leaving the house after awakening or before going to bed, people having long hair, in particular, tend to spend a considerable amount of time for spreading the foam of shampoo throughout their hair or thoroughly rinsing their hair. If a surfactant composition excellent in foam spreadability and foam dissipation property can be formulated in a shampoo, the resulting shampoo enables such long hair to be sufficiently cleansed in a short time, leading to the realization of water-saving.
Then, Patent Document 2 discloses a specific internal olefin sulfonic acid which is intended to impart the solubilizing ability, penetrating ability, and interfacial tension reducing ability as a cleansing component. It discloses that when it is used as, for example, a shampoo, it lathers well without friction, and achieves an improved feel.
Patent Document 3 describes a specific internal olefin sulfonate for the purpose of improving detergency, and discloses examples of application to shampoos, liquid soaps, and the like.
[Patent Document 1] JP-A-01-272564
[Patent Document 2] JP-A-2003-81935
[Patent Document 3] U.S. Pat. No. 5,078,916